The problem is that tags are selected by the game creator, and every creator has a different interpretation of what the tags mean. The alternatives would be tags selected by community consensus and tags selected by a central authority, but these come with their own problems.
FWIW, I agree that static 3D images in a visual novels don't qualify as 3D, but I also don't think being able to rotate the camera is a requirement for a 3D game. Grim Fandango is a 3D game despite having a static camera because the characters themselves can rotate in 3D.